Clinical Features

With the advent of routine immunization of children in the United States, tetanus has become a disease of the elderly, who are particularly susceptible to tetanus due to failure to receive primary immunization or the recommended decennial immunizations. In fact, the majority of Americans over age 70 lack adequate immunity to tetanus.7,8

The exotoxin tetanospasmin is responsible for the clinical manifestations of tetanus, which consist of generalized muscular rigidity, violent muscular contractions, and instability of the autonomic nervous system. Wounds that become infected with toxin-producing C. tetani are most often puncture wounds2 but vary in severity from deep lacerations to minor abrasions.25 Tetanus can also develop after surgical procedures, otitis media, and abortion and can develop in neonates through infection of the umbilical cord and in intravenous drug users.

The incubation period of tetanus, that is, the period from initial inoculation to the onset of symptoms, can range from less than 24 h to longer that 1 month. The shorter the incubation period, the more severe is the disease and the worse is the prognosis for recovery. 1

Clinical tetanus can be categorized into four forms: local, generalized, cephalic, and neonatal. The different categories of clinical tetanus depend on what population of neurons are involved.

Local tetanus is manifested by persistent rigidity of the muscles in close proximity to the site of injury and usually resolves after weeks to months without sequelae. Local tetanus may progress to the generalized form of the disease.

Generalized tetanus is the most common form of the disease and frequently follows a puncture wound to the foot from a nail.2 Of those patients who seek medical care for their initial injury, the majority (more than 90 percent) do not receive appropriate tetanus prophylaxis. 2

The most frequent presenting complaints of patients with generalized tetanus are pain and stiffness in the masseter muscles (lockjaw). 9 Nerves with short axons are affected initially; therefore, symptoms appear first in the facial muscles, with progression to the neck, trunk, and extremities. 9 The transition from muscle stiffness to rigidity leads to the development of trismus and the resultant characteristic facial expression: risus sardonicus (sardonic smile) (Fig 140-1). Reflex convulsive spasms and tonic contractions of muscle groups are responsible for the development of dysphasia, opisthotonos ( Fig 140-2), flexing of the arms, clenching of the fists, and extension of the lower extremities. Patients are completely conscious and alert unless laryngospasm and tonic contraction of the respiratory muscles result in respiratory compromise.

FIG. 140-1. Risus sardonicus (sardonic smile) of tetanus. (From photograph reproduced with permission from the Immunization Action Coalition.)

Disturbances of the autonomic nervous system, generally a hypersympathetic state, occur during the second week of clinical tetanus and present as tachycardia, labile hypertension, profuse sweating, hyperpyrexia, and increased urinary excretion of catecholamines. 10 The autonomic complications of generalized tetanus are particularly difficult to manage and contribute significantly to the morbidity and mortality of the disease.

Cephalic tetanus follows injuries to the head or occasionally otitis media and results in dysfunction of the cranial nerves, most commonly the seventh. This form of tetanus has a particularly poor prognosis.

Neonatal tetanus is an important cause of infant mortality in developing countries and carries an extremely high mortality rate (greater than 90 percent). 9 Because passive immunity from maternal antibodies protects an infant from tetanus, neonatal tetanus occurs only if the mother is inadequately immunized. Most cases of neonatal tetanus arise from unsterile handling of the umbilical stump.

Infants with neonatal tetanus present with weakness, irritability, and an inability to suck in week 2 of life. 1 Tetanic spasms, rigidity, opisthotonic posturing, and a hypersympathetic state develop later.1

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